I have a few questions to atheists, before I become one.

[My imaginary friend is GOD]

I think that I may have not explained correctly - not that my OCD affects my ability to research and work through such issues, it's that I am sure that it is created by the question-"Does God exists?" and the inability to answer it. That's why I am washing my hands all the time, that's why I am making all the other rituals which are considered symptoms of OCD - because I don't know if God exists, so I do them simply because I don't want to risk. That's why I believe that the OCD will be gone when I manage to answer my question.

Honestly, I doubt that. Even if you resolve the question that's plaguing you right now, OCD is usually driven by anxiety and the fear that if you do not perform your rituals, something bad will happen. Whether you identify yourself as an atheist or a theist, that anxiety and fear will likely persist, because even if God does not exist, you may still believe in something like karma or ill will.